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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andrei Vagin <avagin@virtuozzo.com>
Cc: Ingo Molnar <mingo@kernel.org>,
	linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
	peterz@infradead.org, hpa@zytor.com, tglx@linutronix.de
Subject: Re: [2/2] x86/unwind: Make CONFIG_UNWINDER_ORC=y the default in kconfig for 64-bit
Date: Thu, 19 Oct 2017 13:16:55 -0500
Message-ID: <20171019181655.7yjgxuebkqzzcz4f@treble> (raw)
In-Reply-To: <20171019165103.GA15123@outlook.office365.com>

On Thu, Oct 19, 2017 at 09:51:04AM -0700, Andrei Vagin wrote:
> Hi,
> 
> We run CRIU tests for tip/auto-latest regularly, and a few days ago our
> test job started to detect this warning in a kernel log:
> 
> [   44.235786] WARNING: can't dereference iret registers at ffff8801c5f17fe0 for ip ffffffff95f0d94b
> 
> What does it mean? How critical is it?
> 
> Our test job fails if it detects any warning in a kernel log. Maybe we
> need to investigate reasons of this warning and try to eliminate it?
> 
> Here are logs:
> https://travis-ci.org/avagin/linux/jobs/289676634

I think it means the unwinder found some bad ORC unwinder metadata.  Any
chance you have access to the kernel binary?  I need to know what code
corresponds to that ffffffff95f0d94b address.

Or if you can reproduce with the following patch, that should help:


diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 570b70d3f604..95b633f0ce51 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -448,7 +448,7 @@ bool unwind_next_frame(struct unwind_state *state)
 
 	case ORC_TYPE_REGS_IRET:
 		if (!deref_stack_regs(state, sp, &state->ip, &state->sp, false)) {
-			orc_warn("can't dereference iret registers at %p for ip %p\n",
+			orc_warn("can't dereference iret registers at %p for ip %pB\n",
 				 (void *)sp, (void *)orig_ip);
 			goto done;
 		}

  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20171013052544.euk7yawni47lhmdq@gmail.com>
2017-10-13 20:02 ` [PATCH 1/2] x86/unwind: Rename unwinder config options to 'CONFIG_UNWINDER_*' Josh Poimboeuf
2017-10-14 10:49   ` [tip:x86/asm] " tip-bot for Josh Poimboeuf
2017-10-13 20:02 ` [PATCH 2/2] x86/unwind: Make CONFIG_UNWINDER_ORC=y the default in kconfig for 64-bit Josh Poimboeuf
2017-10-14 10:50   ` [tip:x86/asm] " tip-bot for Josh Poimboeuf
2017-10-19 16:51   ` [2/2] " Andrei Vagin
2017-10-19 18:16     ` Josh Poimboeuf [this message]
2017-10-19 22:35       ` Andrei Vagin
2017-10-20  0:38         ` Andrei Vagin
2017-10-20  1:28         ` Josh Poimboeuf
2017-10-20  6:54           ` Andrei Vagin
2018-03-19 18:57   ` [PATCH 2/2] " Matthias Kaehlcke
2018-03-19 19:29     ` Josh Poimboeuf
2018-03-19 20:31       ` Matthias Kaehlcke
2018-03-19 21:20         ` Josh Poimboeuf
2018-03-19 23:22           ` Matthias Kaehlcke
2018-03-20  2:28             ` Josh Poimboeuf
2018-03-20 19:39               ` Matthias Kaehlcke
2018-03-21  2:45             ` Josh Poimboeuf
2018-03-21 21:19               ` Matthias Kaehlcke

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